The proposed work is to continue our investigation on phospholipid metabolism by normal and leukemic leukocytes, and to study the relationship between phospholipid metabolism, phagocytosis and lysosomal enzyme secretion. Emphasis will be placed on phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, and the phosphoinositides. It is planned to measure the labeling of phospholipids by various radiotracers. Isotope incorporation into each lipid will be measured by counting the intact lipid in a liquid scintillation counter, after the lipids are extracted and resolved by thin-layer paper chromatography. It is intended to examine agents that affect phagocytosis and lysosomal enzyme secretion by leukocytes in the metabolism of phospholipids. The fatty acid composition of phospholipids in normal and leukemic cells will be analyzed.